Refrigerating apparatus



Oct. 7, 1941.

H. F. SMITH REFRIG'ERATING APPARATUS Filed oct. 26,

5 Sheets-Sheet l NVENTOR.

ATTORALEYS Oct. 7, 1941. H. F. SMITH I REFRIGERATING APPARATUS 3 Sheets-Sheet 3 Filed Oct. 26, 1938 'INVENTOR.

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ATTORNEYS I U Patented Oct. 7, 1941 REFBIGERATING APPARATUS Harry F. Smith. Lexington, Ohio, assimito General Motors Corporation, Dayton, Ohio, a

corporation oi Delaware Application October 2c, 1938, Serial No. 237,090 11' Claims. 01. 230-222) This invention relates to refrigeration and more particularly to a novel refrigerant compressor mechanism. a

It is an object'of this invention to provide a compressor with a valve which is controlled mechanically during a portion oi the cycle and operates automatically during another portion or the cycle.

Another object of this invention is to provide a compressor with a special sleeve valve.

In the usual form of compressor employing an outlet valve which-is wholly mechanically operated the compressor operates emciently only at certain limited head pressures and back pressures. While it is possible to provide compressors having mechanically operated valves with means for varying the timing of the valve operation so as to allow for variations in the operating pressures,-such timing devices are complicated and'add to the cost of construction. Compressors employing valves which are wholly automatically operated, that is, operated in response topressure, do not operate the most efliciently and are usually noisy in operation. It is an object 01' this invention, thereiore, to provide a compressor with a valve mechanism which incorporates the advantages of the mechanically operated valve as well as the advantages of. the automatically operated valve.

. "Another object of this invention is to provide a valve mechanism which opens'automatically in response to pressure and whichcloses mechanically. I

Further objects and advantages of the present invention will be apparent from the following de- Fig.1 is a view partly diagrammatic showing the compressor mechanism in section; e

Fig. 2 is a fragmentary sectional view'with part Fig. 6 is a diagrammatic view showing the details of a modified form of'valve;

charges intothe condenser I wherein it is con- Fig. 7 is a fragmentary sectional view taken 0 line 1-! of Fig. 6; and

Fig. 8 .is a fragmentary sectional view taken on line 8---8 of Fig. 6. As shown in Fig. 1 the compressor I0 is driven by a motor l2. The compressed-refrigerant disdensed. The condensed refrigerant collects in the usual sump I6 from which it is fed to the evaporator IS in the usual manner. The now of refrigerant into the evaporator I8 is controlled by means of the thermostatic expansion valve 20. The vaporized refrigerant returns to the compressor via the vapor line 22. g The motor I2 iscontrolled by the switch 24. which in turn is i controlled by the back pressure by means of the tion.

bellows arrangement 26 which is of standard construction and therefore needs no further descrip- The compressor i0 is of the reciprocating type and comprises the usual casing 28 in which the vided which is integral with the side walls'oi the sleeve ,38. The-sleeve 36 is .cam operated and has secured to it the cam follower mechanism 42 which cooperates with a'cam 4 provided on the piston.

or the valve sleeve broken away showing the position oi the valve during the intake stroke;

Fig. 3 is a view similar to Fig. 2 showing the position of the valve at the beginning of the compression stroke:

Fig. 4 is a view similar to Figs. 2 and 3 showing the position oi. the valve during the compression strcke'at a time when the pressurev within the compression chamber is substantially equal to the head pressure; p

Fig. 5 shows the position of the valve sleeve at the end oi the compression stroke;

main crankshaft. The sleeve 36 is biased downwardly by means of a compression spring 46 which is mounted between the cylinder head and the cup 48 which rests on the upper end 40 of the sleeve 30. For purposes of illustration the sleeve 36 has been shown as completely surrounding the However. a short sleeve confined to the upper end of the cylinder could be used. The uncompressed gas enters the compression chamher through the inlet I2'which communicates with the recess l4 surrounding the sleeve 26. During the intake stroke the sleeve 38 is in the position shown in Fig. 2 in which position the ports I} are in registry with the recess 54. As

= the piston moves downwardly from the position shown in Fig. 2 the uncompressed gas is drawn into the compression chamber. After the com .pression chamber has been filled with the low pressure gas the cam 44 movesinto the position shown in Fig. 3 wherebythe valve sleeve 36 is moved to a position in which the ports 38 are out of registry with the intake 64. For convenience in description, that portion of the cam surface with which the cam follower 42 is in engagement in Fig. 2 has been designated by the reference character 63, and that surface with which the cam follower is in engagement in Fig. 3 has been designated by the reference character 58.

During the upward stroke of the piston the cam follower 42 rides along the cam surface 63 until such time when the pressure within the compressionchamber exceeds the head pressure, at which time the cam follower 42 is free to leave the cam surface 63 as shown in Fig. 4. The spring 46 tends to move the sleeve in one direction and movement of the piston tends to move the sleeve in the opposite direction. It is appar ent, therefore, that the piston 34 never operates I against a pressure which exceeds the head pressure by any appreciable amount. By virtue of this arrangement the starting torque required is not' excessive since the compression pressure never exceeds the head pressure by any appreciable amount.

Fig. 5 shows both the piston 34 and the valve sleeve 36 in the, uppermost position. It will be noted that in this position the piston covers the ports 33. As the piston moves downwardly from the position shown in Fig. 5, the piston and the valve move together until the port 33 comes into registry with the intake 64. At this point the cam follower engages the cam surface 56 and stops further downward movement of the valvesleeve 36. The piston, however, continues its movement and travels to the end of the suction stroke. By virtue of the above described construction it will be observed that the piston and the valve sleeve 33 move upwardly together when the pressurein the compression chamber is substantially equal to the discharge pressure. It will also be noted that the valve sleeve 36 and piston 34 move downwardly together from the' position shown in Fig. 5 until the inlet ports 33 are in registry with the inlet 64. Referring to Fig. 5 it will be noted that the cam 44 has a cam surface 60 which serves to move the valve sleeve 63 into the uppermost position in which the ports 33 are wholly uncovered. By virtue of this valve arrangement, there is no need for any change in the timing of the valve operating mechanism, and the valve mechanism operates without any valve slap which is common in the ordinary type of pressure-operated automatic valve.

In Fig. 6 rangement in which the valve opens automatically and is closed mechanically. In this modification the compressor casing I0 has a pair of slide rods I2 and I4 slidably supported in the side inlet port. The slide rod I2 carries a camfollower 34 which cooperates'with a cam 36 provided on the main shaft 30. The rod "I2 has a pivotal connection with a lever 33 which is mounted to swing about a stationary pivot 30.

Thefree end of the lever 33 is provided with a valve operating extension 32 which engages.

the shoulder 34 on the main valve 33. In the I have shown a modified valve ar-- position shown in Fig. 6 the siide rod I2 is in its uppermost position and the valve 36 is shown in the fully closed position. The piston 38 is shown in its lowermost position. At the beginning of the compression stroke the slide rod I4 is cammed into its uppermost position by means of the cam I3. As the piston 33 moves upwardly the pressure within the compression chamber gradually increases until it becomes equal to the V discharge pressure at which time a further i.n-

crease in the compression pressure serves to unto pull the slide rod I2 down, and thisdownward' movement causes the extension 32 on the lever 66 to positively close the valve 36.,- By virtue of this arrangement the valve 36 opens automatically when the compression pressure is sufficiently high to unseat the valve and is mechanically closed at the proper time.

The compressed refrigerant passing through the valve 36 flows into the cylinder head I04 from whence it flows into the condenser I06. The condensed refrigerant collects in the sump I08 from whence it flows into the evaporator IIO prior to its return to the compressor intake 02. The compressor is operated by means of the motor II! which is controlled by switch mechanism II4 which operates in the same manner as the switch mechanism 24 described hereinabove.

tion as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claimsiwhich follow. What is claimed is as follows:

1. In a refrigerant compressor, means forming a pumping chamber, a piston within said chamber, inlet and outlet ports for said chamber, a sleeve valve surrounding said piston and controlling the opening and closing of said ports, a crankshaft for operating said piston, cam means on said shaft for operating said sleeve valve, and

means whereby said sleeve valve moves to uncover said outlet port when the compression pressure exceeds the discharge pressure 2. In a compressor for a refrigerating system,

the combination with reciprocating piston and a cylinder cooperating therewith and provided with anexhaust port and an intake port, of a sleeve surrounding said piston and provided with means for covering and uncovering said ports, cam means for reciprocating said sleeve in one direction, and resilient means opposing movement of said sleeve by said cam.

3. In a compressor for a refrigerating system, the combination with a piston and cylinder cooperating therewith and provided with an exhaust port and an intake port, of valve means in direct sliding engagement with said piston for opening and closing said ports, cam operated means for operating said valve during one portion of its cycle of ope'ration, and pressure means for operating said valve the remainder of said cycle.

4. In a gas compressor, a cylinder, inlet and outlet ports for said cylinder, a piston operating within said cylinder, a sleeve valve having a closed end forming one wall of the compression chamber, mechanical means for operating said valve, and means whereby said valve and said piston move in unison when the compression pressure is substantially equal to the discharge pressure.

5. In a compressor, a cylinder, a piston operable therein and forming with said cylinder a compression chamber, an intake port, an outlet port,-a pressure operated valve for said outlet port, valve means for said inlet port, resilient means biasing said outlet valve into closed position, and means in addition to said resilient means for moving said outlet valve'to closed position and positively holding said-valve closed until the start of the suction stroke.

6. In a compressor, a cylinder, a sleeve slidable within said cylinder, an opening in said sleeve, a piston slidable within said sleeve, an inlet port in said cylinder, an outlet port in said cylinder, and means for first moving said sleeve to a position in which said opening is in registry with said inlet port and thereafter moving said sleeveinto a position in which said opening is in registry with said outlet port.

'7. In a compressor, a cylinder, a sleeve slidable within said cylinder, an opening in said sleeve, a' piston slidable within said sleeve, an inlet: port in said cylinder, an outlet port insaid cylinder, and means for first moving said sleeve toaposition in which said opening is in registry with said inlet port and thereafter moving said sleevev into a position in which said opening is in registry with said outlet port, said sleeve and piston being so constructed and arranged that said piston covers said opening at the end of the compression stroke and the first portion of the return stroke.

8. In a compressor, a compression chamber, a

piston movable therein, means for introducing low pressure gas into said chamber, an outlet in said chamber for compressed gas, a pressure operated valve for said outlet, spring means biasing said valve to closed position, and mechanieal means in addition. to said spring means for positivelyclosing said valve at the end of the g compression stroke and for positively holding said valve closed until the start of the suction stroke.

9. In a compressor, means forming a pumping chamber, a pumping element movable in said chamber, means for conveying gas to be compressed to said chamber, an outlet port through which the compressed gas is discharged, valve means for said outlet port, said valve means being so constructed and arranged as to open when the pressure within said chamber exceeds the discharge pressure, a rotary shaft, means whereby rotation of said shaft imparts a pumping movement 'to said pumping element, and mechanical means operated by said shaft for positively actuating said valve means to closed position once during each pumping cyclevand for positively holding said valve closed substantially at the end of each compression stroke.

10. In a'compressor for a refrigerating system, the combination witha piston and cylinder cooperating therewith and provided with an exhaust port and an intake port, of valve means in direct sliding engagement with said piston for opening and closing one of said ports, mechanically operated means for operating said valve during one portion of its cycle of operation, and pressure means for operating said valve the remainder of said cycle.

11. In a compressor, means forming a valve port, a valve member cooperating with said valve port, an abutment on said valve member, means for operating said valve member to closed position, an abutment on said valve operating means, resilient means between said valve member, and said valve operating means biasing said valve member to closed position, said abutments beingv so constructed and arranged as to posi-'' tively actuate said valve me'mber to the fully closed position at the end of the valve closing movement.

HARRY F. SMITH. 

